New research shows that lithium batteries can explode and burn even more violently than previously thought, raising questions about their use and shipment on passenger planes.

It has been widely reported that Malaysia Airlines flight MH370 was carrying a consignment of lithium-ion batteries when it disappeared. Lithium batteries have been linked with a plane crash in Dubai in 2010 and a fire on an aircraft in the US in 2006.

With many airlines replacing paper charts with laptops and tablet computers, the Federal Aviation Administration (FAA) conducted tests on what would happen if one of their rechargeable lithium-ion battery cells ignited. In one test, the cockpit filled with smoke thick enough to obscure instruments and vision out the window for about five minutes.

The FAA's findings, posted on the agency's website, raise an even bigger issue beyond laptops as makers of the battery cells commonly ship the products in bulk in the cargo areas of passenger planes. One test found the batteries may blow up, which may render a plane's fire-suppression systems ineffective.

"That's a result we haven't seen before," said Mark Rogers, director of the Air Line Pilots Association's dangerous goods program. "It's certainly very sobering because that condition could happen on aircraft today."

ALPA is the largest pilots union in North America.

Fires involving lithium batteries have brought down two cargo airline flights since 2010 and prompted the FAA to ground Boeing's 787 in 2013. Both FedEx and United Parcel Service are installing advanced fire-protection systems on their planes to combat battery-fed fires.

The new research also creates a quandary for regulators, which were barred in 2012 by US Congress from imposing standards on lithium battery shipments that would be stricter than those recommended by the United Nations' International Civil Aviation Organisation. The US Department of Transportation and its Pipeline and Hazardous Materials Safety Administration can't enact anything tougher than current ICAO standards unless "credible reports" emerge of actual on-board fires.

"It's set an incredibly high hurdle for us to see further regulations, but that doesn't mean we're not going to keep on pushing for it," said Sean Cassidy, national safety coordinator for ALPA.

PHMSA said on July 31, it's adopting ICAO's recommended standard for lithium battery cargo, which takes effect in the US on February 1, 2015. The regulations will require improved packaging and notification, according to a press release.

Passengers are still allowed to carry their phones, computers and other devices with lithium batteries.

A spokesman for PHMSA, Damon Hill, didn't return phone calls seeking comment on whether the standards are adequate considering the new research.

An ICAO working group of officials from regulation agencies, airlines, unions and battery manufacturers is scheduled to meet on September 9 in Cologne, Germany, to address the new research and determine whether additional restrictions are needed, according to an August 4 letter sent by the agency.

"As more testing is done and new information becomes available, we will continue to factor that data into our efforts," UPS said in an emailed joint statement with its pilots union, the Independent Pilots Association.

Lithium packs are used to power a wide range of products, including Apple iPhones, electronic cigarettes and cameras. The market for rechargeable lithium batteries increased in value to $US11.7 billion ($A12.64 billion) in 2013, from $US3 billion ($A3.24 billion) in 2000, according to AVICENNE Energy, a Paris-based consulting company.

"Unfortunately, the more testing we do, the more concerned we become," Gus Sarkos, manager of the FAA's Fire Safety Branch, said at a conference in Washington sponsored by the pilots association on August 6.

The Rechargeable Battery Association, also known as PRBA, hasn't had a chance to digest the latest FAA test results, said George Kerchner, executive director of the Washington-based trade group.

"It's something that we're going to be looking at," Kerchner said.

Safety is a top concern of manufacturers and they are eager to work with regulators to understand the tests, Kerchner said. The group wrote to ICAO on August 8 seeking awareness campaigns and better guidance on how to ship lithium-based batteries.

There are two major categories of lithium batteries, rechargeable and non-rechargeable, and each burns differently.

US passenger airline flights have been prohibited since 2004 from carrying cargo with non-rechargeable lithium batteries. When they burn, they produce their own oxygen supply and can't be extinguished by fire suppression systems installed on aircraft, according to FAA research.

The rechargeable lithium-ion cells, which can burn more violently, have been allowed to be transported in the belly of US passenger flights since previous testing showed that fire extinguishing systems were capable of containing any explosion.

The new FAA research identified several new hazards in both category of battery.